The present invention relates generally to improving the ability of disc drives to withstand shock events. More particularly, the present invention relates to a system for analyzing the shock performance of individual disc drive components such as a suspension or a read/write head.
The current breed of disc drives spin much faster and are more densely packed with data than prior drives. These speed and size increases require that the read/write heads fly very close to the surface of the disc platters (on the order of a micron). In light of these very low fly heights, the shock performance of a disc drive has taken on paramount importance. Specifically, disc drives must be able to survive large non-operating shocks which are likely to cause an impact between the head and the disc media.
Current disc drive xe2x80x9cshock testsxe2x80x9d utilize a drop test where an entire drive is dropped from a predetermined height at different predetermined angles. The drop test attempts to simulate the types of shocks that will be experienced by disc drives under real world conditions. However, the drop test provides only limited information about the shock performance of a disc drive. Indeed, drop tests are more of a xe2x80x9csurvivabilityxe2x80x9d test where the disc drive is analyzed to see if it can still pass a battery of read/write and seek commands following the drop test.
It is possible to combine disc drive drop tests with real-time analysis of the disc by modifying portions of the disc drive. For example, a top cover of the disc drive may be modified to include an evacuation line for applying a suction to the interior of the drive. In this manner, the modified disc drive could be connected to a particle counter during the drop test to measure the amount of particles generated during the test. However, even such limited whole-drive shock testing is subject to a number of drawbacks.
Specifically, whole-drive shock testing is extremely inefficient due to the requirement that an entire disc drive must be constructed before any testing can be done. There is always pressure to reduce the time-to-market for new disc drives, and thus it is imperative to begin testing the new technology as soon as possible. Long delays may be encountered if shock-related problems are discovered only after production begins on a new disc drive line. Thus, it would be desirable to be able to perform shock tests on individual disc drive components, as opposed to waiting until the components are integrated within a fully functional disc drive.
A further drawback to whole-drive shock testing is that it is difficult to isolate the performance of a single component when the entire drive is subjected to shock testing. That is, due to the large number of interrelated components within a disc drive, it is difficult to measure the shock performance of a single component (e.g., a read/write head or a suspension) since a disc drive may experience a failure for reasons that are not related to the tested components.
Additionally, it is difficult to obtain accurate comparative testing using whole-drive shock testing. Comparative testing comprises, for example, installing two different suspensions or read/write heads within a disc drive and then performing drop tests on the drive to determine which suspension performed better under the shock load. However, it is not a simple matter to build two complete disc drives with different components in order to test the components. Furthermore, as noted above, it is difficult to isolate the performance of a single component when drop testing an entire drive, and this further complicates the effort to perform comparative testing.
In addition to the inefficiencies associated with whole-drive shock testing, prior art drop tests also provide limited value since the test results are not highly repeatable. Specifically, due to the nature of the drop test, it is possible for random events to impact the test results and thereby impair the ability to obtain consistent test results. Furthermore, due to drive yield issues, minor variations between different disc drives also limits the repeatability of shock test results for the above noted reasons (i.e., the same interrelation between the drive components which makes it difficult to isolate the performance of a single component also makes it difficult to obtain highly repeatable test results when two different drives are not identical). Thus, two different disc drives may fail a drop test for two different reasons.
In sum, prior art whole-drive testing is not efficient since it can not be performed until after the disc drive design has been finalized and manufacture of the drives has begun. It would be desirable to perform shock tests on individual drive components earlier in the design effort before time and money is expended to build an entire disc drive. Additionally, current whole drive drop tests do not provide an opportunity to accurately study the shock performance of individual disc drive components. Specifically, current drop tests do not allow researchers to accurately compare two different components (e.g., the mechanical dynamics and particle-shedding nature of two different suspension designs) to determine the better design with respect to shock performance.
The present invention provides a solution to these and other problems, and offers other advantages over the prior art.
In accordance with one preferred embodiment of the present invention, a shock test apparatus is provided for evaluating the shock performance of individual disc drive components. The apparatus includes a base portion and a top cover connected to the base portion to define an interior volume. First and second disc drive components are detachably secured within the interior volume of the apparatus so that the first disc drive component engages the second disc drive component in the absence of a shock event. In this manner, the apparatus simulates a relevant portion of a disc drive when the drive is at rest. A shock pulse generator includes an actuator extending into the interior volume of the apparatus for imparting a shock pulse to the first disc drive component, thereby creating a dynamic interaction or impact between the first and second disc drive components. A second shock pulse generator may also be connected to impart a shock pulse to the second disc drive component to aid in simulating a variety of real world shocks experienced by a disc drive. In one preferred embodiment, the first disc drive component is a head suspension assembly, while the second disc drive component is a media disc (to simulate a Contact Start/Stop disc drive) or a ramp fixture (to simulate a Load/Unload disc drive).
The present invention further includes a system for evaluating the shock performance of individual disc drive components without having to first build a disc drive. The system includes an enclosure having a base portion and a top cover connected to define an interior volume. First and second disc drive components are detachably secured within the interior volume of the enclosure so that the first disc drive component engages the second disc drive component in the absence of a shock event. The system includes a shock pulse generator having an actuator extending into the interior volume of the enclosure to impart a shock pulse to the first disc drive component, thereby creating a dynamic interaction or impact between the first and second disc drive components. The system further includes means for measuring the shock pulse imparted to the first disc drive component, as well as means for measuring the dynamic interaction between the first and second disc drive components. In one embodiment, the system includes a second shock pulse generator having an actuator extending into the interior volume of the enclosure to impart a shock pulse to the second disc drive component as well as means for measuring the shock pulse imparted to the second disc drive component. In a further embodiment, the means for measuring the shock pulses include accelerometers attached to the first and second disc drive components or the actuators used to shock those components, while the means for measuring the dynamic interaction of the two disc drive components includes one of a laser Doppler vibrometer, a particle counter, a particle trap, a sample collection disc, and an acoustical emission sensor.
These and various other features as well as advantages which characterize the present invention will be apparent from a reading of the following detailed description and a review of the associated drawings.